Leviticus 23:5-7

BSB(i) 5 The Passover to the LORD begins at twilight on the fourteenth day of the first month. 6 On the fifteenth day of the same month begins the Feast of Unleavened Bread to the LORD. For seven days you must eat unleavened bread. 7 On the first day you are to hold a sacred assembly; you are not to do any regular work.